In recent years, a multi-zone type air conditioning system has been developed in which a plurality of regions in a passenger compartment is independently cooled and heated. For example, an air conditioning system for independently cooling and heating a front seat region and a rear seat region in a passenger compartment has been developed and used.
As shown in FIG. 1, the air conditioning system includes a compressor 10, a condenser 12, a front seat air conditioning unit 20 for cooling a front seat region in a passenger compartment, and a rear seat air conditioning unit 30 for cooling a rear seat region in the passenger compartment.
The front seat air conditioning unit 20 includes an expansion valve 22, an evaporator 24 and a blower 26 for blowing a cold air of the evaporator 22 to the front region in the passenger compartment.
The rear seat air conditioning unit 30 is installed in parallel with the front seat air conditioning unit 20 with respect to the compressor 10 and the condenser 12. The rear seat air conditioning unit 30 includes an expansion valve 32, an evaporator 34 and a blower 36 for blowing a cold air of the evaporator 34 to the rear region in the passenger compartment.
As shown in FIG. 2, the air conditioning system may further include a battery air conditioning unit 40 if such a need arises.
The battery air conditioning unit 40 is installed in parallel with the front seat air conditioning unit 20 and the rear seat air conditioning unit 30 with respect to the compressor 10 and the condenser 12. The battery air conditioning unit 40 includes an expansion valve 42 and an evaporator 44. The battery air conditioning unit 40 delivers the cold air generated in the evaporator 44 to a high-voltage battery (not shown) of a motor vehicle, thereby cooling the high-voltage battery.
In such a conventional air conditioning system, when at least one air conditioning unit among the plurality of air conditioning units 20, 30, and 40 is already turned on and the remaining air conditioning units are then turned on, a sudden change in refrigerant flow rate may occur in the air conditioning unit in operation. Thus, the temperature of the air discharged into the passenger compartment may become unstable.
For example, when at least one of the rear seat air conditioning unit 30 and the battery air conditioning unit 40 is operated (turned on) while only the front seat air conditioning unit 20 is in operation, the refrigerant of the compressor 10 supplied only to the front seat air conditioning unit 20 is dispersed toward the rear seat air conditioning unit 30 or the battery air conditioning unit 40. In the present invention, the operation of the rear seat air conditioning unit 30 will be described as an example.
Therefore, as shown in FIG. 3A, the amount of the refrigerant supplied to the front seat air conditioning unit 20 sharply decreases. Specifically, the amount of the refrigerant supplied to the front seat air conditioning unit 20 rapidly decreases at the time when the expansion valve 34 of the rear seat air conditioning unit 30 is turned on. This leads to a sharp decrease in the cooling performance of the front seat air conditioning unit 20.
As a result, as shown in FIG. 3B, the temperature of the air discharged to the front seat region rapidly increases from the time when the rear seat air conditioning unit 30 is operated. Thus, the cooling effect of the front seat region is significantly reduced.
Particularly, the temperature of the air discharged to the front seat region is changed until the flow rate of the refrigerant of the front seat air conditioning unit 20 is made stable by way of the control of a refrigerant flow rate in the expansion valve 22. Thus, the cooling effect of the front seat region is significantly reduced. As a result, the comfort in the front seat region is deteriorated.
In the conventional air conditioning system, as shown in FIG. 2, if one of the air conditioning units is turned off in a state in which at least two of the front seat air conditioning unit 20, the rear seat air conditioning unit 30 and the battery air conditioning unit 40 are in operation, for example, if the rear seat air conditioning unit 30 is turned off in a state in which the front seat air conditioning unit 20 and the rear seat air conditioning unit 30 are in operation, the refrigerant supplied to the rear seat air conditioning unit 30 is concentrated on the front seat air conditioning unit 20.
Therefore, as shown in FIG. 4C, the amount of the refrigerant on the side of the front seat air conditioning unit 20 suddenly increases. Specifically, the amount of the refrigerant on the side of the front seat air conditioning unit 20 suddenly increases at the time when the expansion valve 34 of the rear seat air conditioning unit 30 is turned off. Thus, the cooling performance of the front seat air conditioning unit 20 is excessively increased.
As a result, as shown in FIG. 4D, the temperature of the air discharged to the front seat region is excessively lowered from the time when the rear seat air conditioning unit 30 is turned off. Eventually, the front seat region is overcooled.
Particularly, the temperature of the air discharged to the front seat region is changed until the flow rate of the refrigerant of the front seat air conditioning unit 20 is made stable by way of the control of a refrigerant flow rate in the compressor 10 or the expansion valve 22. Thus, the front seat region is overcooled. As a result, the comfort of the front seat region is significantly deteriorated.